backends/drm: add support for adaptive backlight modulation
This feature reduces backlight power, and compensates for the reduced brightness by increasing contrast of colors on the screen.
As this changes colors a lot, this feature is opt-in and forcefully disabled if color accuracy is preferred.
Also see https://lists.freedesktop.org/archives/dri-devel/2025-July/516012.html for the kernel side
Depends on libraries/plasma-wayland-protocols!79 (merged). Also check out libkscreen!189 (merged) and kscreen!486 (merged)
Edited by Xaver Hugl